Don't ask to hold the baby. No matter how cute he is. No matter how much you think Kate is eyeing up lunch and needs her hands free, no matter how much you worry her arms are tired, no matter how much she may need to answer her cell (do royals carry cells?). There will be people hired to hold the baby and you aren't one of them, so calm your clucky down and step away.

Manners apply. It would be advisable to swallow your food before launching into conversation, to have clean hands if you're going in for a shake, to check your teeth for parsley, to deodorise, to keep conversation light.

In the past, etiquette coaches have told those making the royal acquaintance not to initiate a chat, but if you've got a window . . . hell, you'll probably only get one chance.

Just don't start with any of the following:

"So, when are you having number two?" This is an inappropriate and awkward question when aimed at someone you know, let alone royals. On that note, stay away from any implication they have a sex life ("have you started trying for number two yet?) as this will only end in blushes all round and you will look like a total creep.

"Gosh, your sister has a great bum!" It's true, she does, but Pippa stole the limelight for months after The Wedding - best not bring it up years after the fact. Perhaps no mention of Pippa whatsoever, or Harry - everyone's favourite loveable rogue.

"Can I give you my card?" Nice try, but chances are they have all they need and you will never be useful to them in any way whatsoever.

"I still remember where I was the day your mother died." Umm . . . so?

And no line about being royal, or never being royal, or any other dad jokes relating to certain New Zealand music royalty - it won't be funny if they get it and it won't be funny if they don't.

THERE are old-school ways to meet and greet the royals. These involve men doing a deep nod of the head and women a small curtsy. Thank goodness it's acceptable these days for people to go in for a simple handshake - we Kiwis are not well versed in bows and curtseys. But wait for them to offer a hand first. Practise your squeeze levels on a trusted friend, because you don't want to be a wet fish and you don't want to be breaking anyone's fingers. A quick wipe down the side of your clothes to get rid of possible hand sweat may be beneficial for all parties, also.

Kensington Palace chief press secretary Ed Perkins plays down the need to outline any royal visit protocol, but he would say this:

"Traditionally, the duke and duchess are referred to in the first instance as "Your Royal Highness" and thereafter as "sir" or "ma'am".

"But it really is whatever people feel most comfortable with. The couple are most interested that people meeting them should be relaxed and enjoy the occasion, not worry too much about etiquette."

With this in mind, if you're comfortable with a "howzit bro," that would be just fine. Not sure how it will go down on YouTube, but the duke and duchess probably won't be fazed.

If you do want to attempt the old-school greet, remember it's ma'am rhymes with SPAM, not ma'am rhymes with CHAAARM - but it sounds horrific, no matter which way you say it. You may disagree, but perhaps stay right away from calling them anything at all. A simple "so great to meet you" is plenty.

THIS brings us to the overall tone with which you address the duke and duchess. You want to pitch it somewhere between the voice you use among friends and the voice you put on when you answer the phone to find someone of importance on the other end. Maybe practise this, too, in case it comes out wrong and you sound Irish or something.

If you are prone to catching accents off other people, try to be conscious of this fact, because "oh hiiiiiii Maaaarrrrrmmmm, I simply adoooooooore your Dolce & Gabbaaaaaana haaaandbaaaaaag," is so far gone on the scale of cringe factor, it will tip the world into armageddon. And don't watch Downton Abbey in the 24-hour leadup, or it's guaranteed you will channel Mrs Patmore far more than Lady Mary.

Best not to touch Prince William and/or Catherine. They might break. Michelle Obama caused a right royal stir when she put her arm on the Queen's back in 2009 (Paul Keating did the same in 1992) and both have been rolled out many a time in the royal not-to-do's.

And a few other notables for the real diehards: Don't wear the matching sapphire and diamond engagement ring you bought from iheartwillsandkate. com, or certainly don't point it out. Don't wear the replica you made of the Burberry dress you saw the duchess wearing. Don't get drunk pre meet'n'greet to calm the nerves.

There are a raft of people who are waiting for their five seconds, so don't be a royal hog. Consider buying (or borrowing) a corgi - it could give you the edge you need to look as royal as you'll ever look. Who knows? Maybe you'll arouse the curiosity of the duke.

And remember, they are only royals. You may get the chance to meet them again in your lifetime - but probably not, so don't screw this up.